The analysis of the nonairport operations impact frequency for all categories of
aircraft is based on the same four-factor formula (Equation 5-1) as is used for
airport operations; i.e., the frequency, Fj, for the class of aircraft, j, is
where the product NP represents the expected number of in-flight crashes per
year; f(x,y) is the probability, given a crash, that the crash occurs in a
1-square-mile area surrounding the facility of interest; and A is the effective area
of the facility. Ideally, values for NP and f(x,y) would be provided for any location
within the continental United States (CONUS), similar to those provided for airport
operations. However, this is impractical because of the large area of the CONUS.
For this standard, values of the product NPf(x,y) applicable to selected DOE sites
are provided in Tables B-14 and B-15. Also included are minimum, U.S. average,
and maximum values, which can be used for facilities at other locations within the
CONUS, for each category of aircraft.
Development of the values in the tables is based on an analysis of the locations of
past aircraft crashes within the CONUS. For general aviation, this record is
substantial (over 1000 crashes) while the available data for other aircraft
categories/subcategories, e.g., air carrier and large military, are very limited.
Discussion of the bases of the values in Tables B-14 and B-15 and an outline of
the analysis steps follow.
General Aviation. The distribution of general aviation (GA) aircraft
crashes throughout the CONUS is based on GA aircraft flying under both
VFR and IFR conditions. Except for certain restrictions, e.g., restricted
airspace, a GA aircraft can fly almost anywhere in the CONUS. In
addition, once an in-flight mishap does occur, with an eventual loss of
control, there is nothing to prevent a disabled aircraft from crashing into
any location, even within a restricted airspace area. Thus, it is